Car battery suddenlly going flat

[Andy_Pagin]

1997 Ford Explorer.
The car's been running fine beforehand, but the day before yesterday it would barely turn the engine before giving up completely. So took the battery out and left it on charge all day. Next time I tried starting it it was fine, went shopping, involving three stops/starts, no problem, This afternoon it's dead again.

The battery's only a year old.
Did some basic testing after a jump start, with the tests done after disconnecting the jump leads.
Engine-off voltage 12.5v
Engine idling 14.19v, revving 14.23v.
Engine off and key out current draw about 0.2 amps.

What's the most likely culprit?
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[Riejufixing]

I'd guess the battery.

[jeffyjeff]

You should be able to take your battery to a local auto parts store, the place you bought it from, for example. Have them load test it for you. They will likely do it for free, or for a very nominal fee. If it fails, most likely it is under warranty, and you can get another for a prorated discount, maybe for free.

0.2 Amperes is pretty high parasitic drain on your battery, according to this article. Make sure all the doors and trunk lid are shut when you measure.

https://www.popularmechanics.com/cars/car-technology/a5859/how-to-stop-car-battery-drains/#:~:text=Most%20vehicles%20draw%20some%20battery,many%20vehicles%20will%20draw%20less.
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History shows again and again how nature points out the folly of men - BOC

[UncleFester]

Cold has done one or more of the cells in, bet it fails the test. Every time I've had this its been a duff battery.

Alternator ok? Diode gone bad?
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2017 Z1000SX

[WD Forte]

Parasitic drain can be misleading.
On my Galaxy its initially say 200-300mA as not all systems shut down immediately but this drops in time to around 40mA.
I learned it can take around 10-12 minutes for this to happen and it's
just the way the cars system works.
TLDR:
Parasitic drain tests may take a while to do properly

Re your battery, it may just be a duff one.
I bought a calcium type that was a PITA and never seemed to hold
a charge long and I binned it after a year for a more conventional
type which has been great even though the car stands unused for long ish periods.
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[xX-Alex-Xx]

Either a duff battery or something like the alarm is draining it. Best way to find parasitic draw is to pull fuses until you see the draw drop off. You'll then have an idea of what circuit is draining.
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[jeffyjeff]

[bugeye_bob]

[MCN]

0.2 amp is probably clock/alarm.
Smells like the battery has a short.

Charge and have it load tested.

A load test does what the starter motor does to the battery.
Some vehicles it is possible to even use the starter to load test (as a load tested does.)
Needs two people or some Eff-Off long test leads.
Foot on the brake.
Top gear.
Engage clutch.
The starter.
Observe battery volts.
Shouldn't drop below 10volts.
Don't test more than 5 seconds.
The wires and stuff can get too hot.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[jeffyjeff]

[MCN]

[jeffyjeff]

not implying anything, sir. You are right and I agree with you.
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History shows again and again how nature points out the folly of men - BOC

[MCN]

[jeffyjeff]

Well, it means I concur with you:
First and foremost, I agree that using the starter circuit can be an effective way of load testing a battery.
I also agree that such testing must be executed in a manner that limits the time that power is applied to the circuit when the engine is prevented from turning over.
I agree that 5 seconds is a reasonable period for anyone to power the starter circuit, take the voltage reading, and conclude the test.
I concur with the statement that “wires and stuff can get too hot” and offer an example to support the claim. Here is why:
a. The starter windings are the most fragile conductors in the starter circuit (smallest wire gauge).
b. The starter is designed to operate with the armature turning. Current draw through the motor increases as load (rotational resistance) is applied to the armature.
c. Maximum load is reached when the armature is locked.
d. Maximum current draw and heat is generated when the armature is locked.
e. Heat can melt the enamel wire insulation in the field windings, leading to catestrophic failure.
f. Excessive current can fuse the brushes to the commutator, leading to catestrophic failure.
To limit the potential for a catistrophic failure, connect your meter before initiating the test, and conclude your test as quickly as possible. It is possible to get the voltage reading in well under 5 seconds.
____________________
History shows again and again how nature points out the folly of men - BOC